It is known that cellulose acetate filaments or fibers have a good dyeing property, which causes the dyed cellulose acetate filaments or fibers to have a vivid color and a high colorfastness, and a silk-like look, and, therefore, that such filaments or fibers are useful for various products, for example, clothing, especially, fashionable clothing.
Generally, conventional cellulose acetate filaments or fibers are produced by a dry spinning process, in which a spinning solution of a cellulose acetate in an organic solvent, such as acetone, is extruded through a number of spinning holes. The resultant filamentary streams of the cellulose acetate solution are solidified by rapidly evaporating the solvent from the filamentary streams. This evaporation of the solvent is rapidly completed, usually within a period of 0.6 seconds or less. Accordingly, the resultant conventional cellulose acetate filaments or fibers inherently have a smooth and soft touch, and a greasy feel, but not a natural silk-like rough and rigid touch, and dry feel. Accordingly, the conventional cellulose acetate filaments or fibers are useless for producing, for example, fashionable clothing which exhibits a natural silk-like rough and rigid touch and dry feel.
In order to modify the touch of the conventional cellulose acetate filaments or fibers, a number of approaches have been attempted.
In one approach for modifying the conventional cellulose acetate filaments or fibers so as to exhibit a natural silk-like rough and rigid touch, and dry feel, a pigment, for example, titanium oxide, blended to a cellulose acetate flakes and the blend was subjected to a fiber-forming process. However, this approach was not successful because the resultant filaments or fibers exhibited a poor mechanical strength, and therefore, were useless for practical use.
In another approach, the cellulose acetate to be converted into filaments or fibers were chemically modified with, for example, hydrolysis. This approach also resulted in a poor mechanical property of the filaments or fibers.
In still another approach, the filaments or fibers were produced from a blend of two or more types of cellulose acetate flahes which were different in acetyl value from each other. However, this approach also caused the resultant filaments or fibers to exhibit a poor mechanical property.